Subcerebral ischemia may occur as a result of thrombus, heart failure associated with low cardiac output, cardiac arrhythmias, low blood pressure or other cardiovascular events. Subcerebral ischemia may manifest as a stroke or transient ischemic episode. Methods for detecting subcerebral ischemia may include Magnetic Resonance Imaging (MRI), Positron Emission Technology (PET), or biological marker measurements taken from the patient's blood. These methods can be time-consuming, costly, or not readily available. Even with sophisticated imaging technology, the detection of subcerebral ischemia can be challenging. A need remains for an apparatus and method for detecting subcerebral ischemia.